#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int Fibo(int N)
{
	if (N<=2)
	{
		return 1;
	}
	else
	{
		return Fibo(N - 1) + Fibo(N - 2);
	}
}
int main()
{
	int n = 0;
	scanf("%d", &n);
	int ret = Fibo(n);
	printf("%d\n",ret);
	return 0;
}